The present invention relates to a tool including a pair of movable arm members each of which supports a different working jaw, and a drive arrangement for moving the arm members between a closed position corresponding to closing of the jaws and an open position corresponding to opening of the jaws. Each arm member forms part of a force transmitting path extending between a point on the tool to which an external operating or supporting force is applied and a corresponding working jaw whereat the force is transferred to an article held in the jaw.
A tool constructed according to the present invention can be used for handling, e.g. gripping, or holding an article between the working jaws of the tool, or for performing an operation on the article such as crimping, pressing or cutting. The arm members of the tool can be pivoted relative to one another (tong-type tool) or move in a translatory manner relative to one another (vise-type tool), both types of tools hereinafter being referred to as a "tool of the kind specified". Tongs, pliers, clamps, vises and the like are all examples of a tool of the kind specified. The drive arrangement may include, for example, a pair of handles or a pneumatically or electrically driven actuating lever.
The term "working jaw" as used herein refers to the particular part of the tool which is adapted to perform a desired operation. Each working jaw is provided with, for example, dies, grooves, planar pressing faces or cutting edges. The term "arm member" refers to the tool part which carries or supports the working jaw, and the term "force transmitting path" which refers to those interconnected and cooperating structural parts of the tool which extend between a part to which an external force is applied, e.g., one of the tool handles, and a part which applies a force to an article, e.g., the working jaw operatively associated with the handle. Thus, the operating or supporting force applied to the tool is transferred through a force transmitting path to the article being worked on by the tool.
In the case where the drive arrangement includes a pair of handles or an actuating lever, at least one pivotal connection is provided between the arm members and/or at least one of the two handles (or the actuating lever). Each of the handles can also be pivotally connected to corresponding arm members. The connections between the handles and the arm members can also be rigid, or one handle can be pivotally connected to a corresponding arm member and the other handle rigidly connected to its corresponding arm member to define an elongated tool body.
The tool of the present invention is preferably provided with a motion control mechanism such as a ratchet-and-pawl mechanism which prevents opening of the working jaws before a working stroke of the arm members is completed.
Tools having a pair of handles and working jaws which move in a translatory manner relative to each other are known. In these tools, one working jaw may be rigidly connected to a corresponding handle and the other working jaw may be connected to the other handle through an intermediate link including two pivotal connections.
The tool constructions described above are conventional. An example of a pliers for crimping terminal ferrules onto the ends of electrical conductors wherein one handle is rigidly connected to a corresponding arm member and the other handle is pivotally connected to the other arm member, and both arm members are interconnected by an intermediate link is shown in British Pat. No. 1,522,144 of one of the present co-inventors. In some cases, e.g., when crimping terminal ferrules onto the ends of electrical conductors, and particularly when a motion control mechanism is provided, it is desirable to apply a greater working force to larger articles than to smaller ones. It will be appreciated that such a requirement may also arise for other applications of a tool of the kind specified.
One solution which has already been proposed calls for the placement of a separate resilient member in at least one of the force transmitting paths of the tool. The resilient member may be positioned, for example, between an arm member and its associated working jaw, or between an arm member and an associated member of the driving arrangement (e.g., handle) or between an arm member and an associated stationary part of the tool which supports the arm member.
An object of the present invention is to provide a tool of the kind specified wherein a resilient member is placed in a force transmitting path so that the tool construction is simplified and the use of materials such as rubber or polyurethane for the resilient member, which materials have a shorter lifetime than materials such as steel which form the remainder of the tool, can be avoided.
Another object of the present invention is to provide a method of attaching a working jaw to an associated arm member so that the tool can be constructed at lower cost.
In accordance with the present invention, a tool includes two arm members arranged for relative movement, and a pair of working jaws each supported on a different one of the arm members. A drive arrangement is connected to at least one of the arm members to move the arm members between open and closed positions in response to an externally applied operating force. The drive arrangement, the arm members and the working jaws provide two force transmitting paths each extending between a different point at which an external force is applied to the tool, and an associated working jaw whereat the external force is transferred to an article to be worked by the tool. At least one pivot member is mounted in the force transmitting path for pivotally connecting any two of the group including the working jaws, the arm members and the drive arrangement to one another. A resiliently yieldable bearing member is provided for contacting the pivot member.
In a preferred embodiment, at least one of the arm members is formed by two spaced apart, generally planar, parallel arm plates, and one of the working jaws extends into the region between the arm plates. The arm plates and the working jaw between them each have at least two sets of aligned openings at spaced apart locations therein. At least two elongated retaining members each pass through and are closely fitted in a corresponding set of the aligned openings to fix the working jaw to the arm plates.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention .